As the digital camera technology advances rapidly in recent years, various electronic devices (such as digital cameras, camcorders, notebook computers and mobile phones, etc) with an image capturing device are introduced constantly to the market. Not only the quality becomes increasingly higher, but the volume of products also becomes increasingly smaller, and their market price becomes lower gradually. These electronic image capturing devices available in the market become popular, and thus finding a way of designing an electronic device having a smart image capturing function to meet the image capturing requirements of the extensive consumers and compensate their deficient photographic skills is an important subject for electronic image capturing device designers and manufacturers to study and provide feasible solutions.
A portrait photo is the most popular type of photos taken by a traditional electronic image capturing device by consumers. When a portrait photo is taken, a series of searches is performed to capture the most appropriate transient scene, so that the portrait photo taken shows the best appearance of the photographed person. What is the best acceptable appearance recognized by a vast majority of consumers? Perhaps, the answer is an appearance of a photographed person with a smile face and opened eyes. Therefore, we usually expect a photographer to take our portrait photo at the moment when we are showing a smile face. Unfortunately, the photographed person does not know the exact time when the photographer presses the shutter due to a lack of communication or unspoken consensus and thus they usually close their eyes or mouth unintentionally while the photographer is taking their portrait. Even worse, the facial expression becomes unnatural or stiffed when the photographed person is told to maintain a smile face for a long time, but the person cannot keep still so long. Sometimes, the photographed persons may show a serious facial expression or blink their eyes after such a long smile while the photographer is taking the picture. Such unexpected situation gives rise to a portrait of a person with unnatural and stiff facial expressions, which is unsatisfactory or unacceptable to most photographed persons.